This invention concerns a device for maintaining and changing the pressure in tires.
There are different methods for re-inflating a tire when using an integrated pump that is driven by the tire deformation, the rotation of the wheel, by using an electronic device or by pressure changes in the tyre, etc. All of these systems are used for compensating for under-inflation by re-inflating the tire with ambient air to the pressure specified by the tire manufacturer. Any excess of air may then be released from the tire. This solution requires the purification of the air and communication between the interior and exterior of the tire that might cause contamination. Re-inflation through the exterior of the tire is a relatively lengthy process, however. In the case of a valve failure the tire can become completely deflated, which creates a dangerous condition. The purpose of the device described below is to reduce or to avoid the need for tire inflation by using ambient air.
Based on this invention, the drawbacks described above have, to a large extent, been eliminated by the device for maintaining and changing the pressure in tires. Its operational principle is based on a pump that interconnects the interior of the tire with an accumulator that is supplied with at least one pressure control element at its inlet and/or outlet to the interior of the tire.
The pressure accumulator can either be connected to the tire and/or to the inner tube and/or the rim and/or it can constitute an integral part of the tyre, the inner tube, or the rim. This, in effect, has the advantage that the pressure accumulator is fitted with an additional inlet for ambient air or with an air outlet to the exterior of the tire. Based on this advantageous design, the pump is connected at one end to the interior space of the tire and/or with the exterior of the tire and/or the accumulator and at the other end it is connected with the interior of the tire and/or the exterior of the tire and/or the accumulator.
The principle that this invention also represents is as a device for maintaining and changing the pressure in tires when the pump is a peristaltic pump in the form of a deformable hose positioned on the perimeter of the tyre, i.e. anywhere on tire both including tread and sidewall, inside the tire wall, or on the tire wall or near the tire wall from outside or inside of the tire. The hose is fitted with both an air inlet and outlet, while these are placed apart from each other on the tire perimeter, separated at a preset length, in accordance with the deformation of the tire.
The pump is provided with at least one valve. This means that there will be a section with a minimum volume capacity at the inlet and/or outlet of the pump. The pump can be fitted with a valve, i.e. a three-way valve, with inputs for a pump source and a pump target and while one input is fitted to the valve, the second is connected to the pump and the last input is connected to the closure fixture.
A ring is attached to the inner side of the pump and the distance of its outer edge from the axis of the tire rotation is equal to between a 1 to 1.1 multiple of the distance of the bottom side of the pump from the axis of the tire rotation. The pump has the form of a curved hollow channel with at least one of its outer walls partially formed by the sections of two planes that lie in the same longitudinal direction as the pump, forming an angle of α=0 to 120°, while if α>0°, it is located at the contact edge of these two planes, situated on the far side from the centre of the cross-section of the pump.
The principle of the invention also represents a tire and/or rim and/or inner tube containing an adhesive and/or a profile lock for interconnection with any element from the group of the tire and/or rim and/or inner tube and/or pump.
Additionally, the principle of the invention is a tire and/or rim and/or inner tube and/or pump, modified for the placement of any device, in accordance with the above described requirements.
Another principle of the invention is the above described device which constitutes a part of the tyre, inner tube, and/or rim.
A major advantage is that, compared to the familiar system whereby pressure is adjusted by releasing air externally or by refilling with air from outside, this device does not need to be re-inflated with air from outside, thereby avoiding contamination, possible corrosion, and tire failure. Following a drop in the pressure the air is refilled from outside and in the case of excess pressure the air is released to the exterior. Frequently the tires are cold-inflated to a certain pressure level and then, after reaching the presumed temperature, the pressure adjusts to the previously estimated level which, in principle, is a compromise pressure that has been calculated theoretically for the entire nexus—the specific type of tyre, the vehicle, the environment, etc. Therefore the tire doesn't reach the pressure level required in operation until it has warmed-up and even when it is warmed-up the pressure, at best, is close to its ideal status only in a random number of the targeted tires. Based on our model the tyre-accumulator system may simply be overinflated, while the pressure inside the tire is actually ideal, regardless of the temperature and the other operating conditions. It remains true that in our model this can be achieved without any exchange of air with the external environment and even without the need for a valve when the system consists of only a simple pump and an accumulator. The built-in accumulator can ensure a rapid change of pressure when, for example, prior to the vehicle moving through a curve the air from the accumulator is transferred to the selected tyre, which alters its tread contact, and the air is subsequently returned to the accumulator. Or vice versa—in a racing car, for example, the tires rapidly become overinflated on the straights and therefore the tire has minimal resistance and it then deflates and reaches the ideal level of tread contact in the bends.
The peristaltic pump design described here is also simplified to the utmost and a simple hose of the appropriate length can achieve the re-inflation or the deflation of the tire to the pressure that provides the required tread contact. This simplicity of operation increases the reliability of the device, while at the same time reducing its cost.